An example of a gear-driven bearing unit of this kind is disclosed in US 2004/0244521. The unit comprises a toothed connection element and an untoothed connection element, between which one or more rows of rolling elements are arranged. The unit further comprises a housing and worm gear or a spur gear for driving the toothed connection element. Part of the housing is connected to the untoothed connection element and axially encloses the toothed connection element at one side. A further part of the housing radially encloses the toothed connection element. The unit is lubricated with grease and comprises sealing rings for sealing a gap between the housing and the toothed connection element and a further gap between the toothed connection element and the untoothed connection element. The sealing rings are designed to allow grease to escape via the sealing rings when the unit is filled with new grease.
The unit disclosed in the above-mentioned US application is therefore designed to facilitate relubrication. The prescribed relubrication interval for commercially available gear-driven bearing units typically lies in the order of several months. The refilling of a unit with fresh grease is a time-intensive procedure, leading to high maintenance costs, especially when many such units are located at a site.
Consequently, there is room for improvement.